Polymers enjoy an expanding range of application. Conjugated polymers have been widely recognized for their potential as inexpensive and versatile electronic materials for many applications. Because of their wide-ranging applicability, major efforts have been focused on determining the relationship between the polymer chemical structure and conformation and the corresponding physical and chemical properties of polymer materials. Common efforts have focused on altering polymer properties by modifying the polymer conformation through changes in the polymer/monomer design and through synthesis steps that change the conjugated repeat units of the polymer.
For example, the fluorescence emission wavelength may be tuned over the entire visible range to obtain variable-color LEDs by varying polymer substituent groups to tune the π-electron density. The fluorescence can be further tuned over an additional 100 nm by varying the repeat unit to construct polymers with varying degrees of rigidity. These methods also affect the conductivity and quantum efficiency of fluorescent polymers. One of the most challenging aspects of these prior art methods is that a polymer's properties are altered by changing the repeat unit conformation of that polymer. This means that a new polymer must be synthesized for each desired variation of the polymer's electronic or photophysical properties.
Prior work of mine and others at Los Alamos National Laboratory related to polymer-surfactant complexes exhibiting many other improved photophysical properties; the properties and the degree of improvement may vary depending on the polymer and surfactant used to form the complex. These complexes may exhibit flourescence quantum efficiency improvement by a factor ranging from 2 to 20, or more, when compared to the next polymer. Complexes according to my prior work may have emission spectra that are excitation wavelength independent. They may have absorption spectra that are narrowed and red-shifted when compared to the neat polymer. The fluorescence of the polymer-surfactant complexes may also be characterized by single exponential decay kinetics rather than the less stable, multi-exponential decay characteristics of neat polymers. The polymer-surfactant complexes of my prior work were very important, but one area in which they were lacking was in well defined solid state materials. When dried, the previous polymer surfactant materials resulted in large agglomerates, many of which lost important physical properties during precipitation. Moreover, the precipitants as large agglomerates are not as useful as smaller particles.